In a manufacturing process of a semiconductor device or a flat panel such as a liquid crystal display or the like, a substrate called a semiconductor wafer (hereinafter simply referred to as “wafer”) or a glass substrate accommodated in a carrier, and after the carrier is loaded into a loading port of a semiconductor manufacturing apparatus (including a flat panel manufacturing apparatus), the substrate is taken out of the carrier by a transfer arm in the apparatus and then is transferred into a processing module. In case that the processing module is a vacuum processing module of a single sheet type or a spinner used in a resist process or the like, it is required to align the center of the substrate with the center of a mounting unit in the module with a high accuracy. Thus, the quality of the performance of the transfer arm affects a processed result of the substrate.
One example of such substrate processing apparatus is a so-called multi-chamber system including a plurality of processing chambers (processing modules) for performing an etching process or a film forming process by CVD (Chemical Vapor deposition); and a common transfer chamber having a transfer arm therein and connected with the respective processing chambers. In the film forming process or the etching process, the wafer needs to be accurately mounted on a predetermined position in each processing chamber. If the mounting position of the wafer is deviated, there may be incurred non-uniformity between wafer surfaces in view of obtained film thicknesses, etched line widths, and so forth.
To solve this problem, an example technique for improving the accuracy of the transfer position of the substrate (hereinafter, referred to as “controllability”) transferred into the substrate processing apparatus such as the multi-chamber system is disclosed in Patent Document 1 wherein a transfer arm of a joint type (frog leg type) is given an improved controllability by suppressing a deterioration of a movement resolution in a state that the transfer arm is extended. Further, Patent Document 2 discloses a transfer arm a joint type (scalar type) having a conveyance mechanism in an arm unit constituting the transfer arm.    [Patent Document 1]: Japanese Patent Laid-open Publication No. 2000-100888 (Paragraph [0038] and FIG. 1)    [Patent Document 2]: Japanese Patent Laid-open Publication No. 2000-72248 (FIG. 2)